[es7] implement exponentiation operator proposal

test/webkit/fast/js/parser-syntax-check-expected.txt

 # Copyright 2013 the V8 project authors. All rights reserved.
 # Copyright (C) 2005, 2006, 2007, 2008, 2009 Apple Inc. All rights reserved.
 #
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 #     notice, this list of conditions and the following disclaimer in the
@@ skipping 39 matching lines @@
 PASS Valid:   "a: b: c: new f(x++)++"
 PASS Valid:   "function f() { a: b: c: new f(x++)++ }"
 PASS Valid:   "(a)++"
 PASS Valid:   "function f() { (a)++ }"
 PASS Valid:   "(1--).x"
 PASS Valid:   "function f() { (1--).x }"
 PASS Invalid: "a-- ++"
 PASS Invalid: "function f() { a-- ++ }"
 PASS Invalid: "(a:) --b"
 PASS Invalid: "function f() { (a:) --b }"
-PASS Valid:   "++ -- ++ a"
-PASS Valid:   "function f() { ++ -- ++ a }"
+FAIL Valid:   "++ -- ++ a" should NOT throw 
+FAIL Valid:   "function f() { ++ -- ++ a }" should NOT throw 

[caitp (gmail), 2016/02/08 22:09:44]

The grammar change in the latest version of the proposal might be a bit
dangerous because of these ReferenceErrors becoming early errors /cc rwaldron
(but I assume people have been okay with this so far?)

[caitp (gmail), 2016/02/09 23:09:09]

In implementations today, it's a ReferenceError at runtime, rather than a
SyntaxError (although it might actually just be an early ReferenceError)

[Dan Ehrenberg, 2016/02/11 08:16:50]

Yeah, good to call this out as dangerous. Let's do this change in another patch.
We have other things that the spec says should be SyntaxErrors, but we currently
make errors at runtime; maybe they should be changed, but it'd be good to
collect some more data before shipping. Shouldn't be too hard to add a
UseCounter (as I recently did for for-in-initializer), should it?

 PASS Valid:   "++ new new a ++"
 PASS Valid:   "function f() { ++ new new a ++ }"
 PASS Valid:   "delete void 0"
 PASS Valid:   "function f() { delete void 0 }"
 PASS Invalid: "delete the void"
 PASS Invalid: "function f() { delete the void }"
 PASS Invalid: "(a++"
 PASS Invalid: "function f() { (a++ }"
-PASS Valid:   "++a--"
-PASS Valid:   "function f() { ++a-- }"
-PASS Valid:   "++((a))--"
-PASS Valid:   "function f() { ++((a))-- }"
+FAIL Valid:   "++a--" should NOT throw 
+FAIL Valid:   "function f() { ++a-- }" should NOT throw 
+FAIL Valid:   "++((a))--" should NOT throw 
+FAIL Valid:   "function f() { ++((a))-- }" should NOT throw 
 PASS Valid:   "(a.x++)++"
 PASS Valid:   "function f() { (a.x++)++ }"
 PASS Invalid: "1: null"
 PASS Invalid: "function f() { 1: null }"
 PASS Invalid: "+-!~"
 PASS Invalid: "function f() { +-!~ }"
 PASS Invalid: "+-!~(("
 PASS Invalid: "function f() { +-!~(( }"
 PASS Invalid: "a)"
 PASS Invalid: "function f() { a) }"
@@ skipping 234 matching lines @@
 PASS Invalid: "function f() { if (a) if (b) ; else function (){} }"
 PASS Valid:   "throw a"
 PASS Valid:   "function f() { throw a }"
 PASS Valid:   "throw a + b in void c"
 PASS Valid:   "function f() { throw a + b in void c }"
 PASS Invalid: "throw"
 PASS Invalid: "function f() { throw }"
 var and const statements
 PASS Valid:   "var a, b = null"
 PASS Valid:   "function f() { var a, b = null }"
-FAIL Valid:   "const a = 5, b, c" should NOT throw
-FAIL Valid:   "function f() { const a = 5, b, c }" should NOT throw
+FAIL Valid:   "const a = 5, b, c" should NOT throw 
+FAIL Valid:   "function f() { const a = 5, b, c }" should NOT throw 
 PASS Invalid: "var"
 PASS Invalid: "function f() { var }"
 PASS Invalid: "var = 7"
 PASS Invalid: "function f() { var = 7 }"
 PASS Invalid: "var c (6)"
 PASS Invalid: "function f() { var c (6) }"
-FAIL Valid:   "if (a) var a,b; else const b, c" should NOT throw
-FAIL Valid:   "function f() { if (a) var a,b; else const b, c }" should NOT throw
+FAIL Valid:   "if (a) var a,b; else const b, c" should NOT throw 
+FAIL Valid:   "function f() { if (a) var a,b; else const b, c }" should NOT throw 
 PASS Invalid: "var 5 = 6"
 PASS Invalid: "function f() { var 5 = 6 }"
 PASS Valid:   "while (0) var a, b, c=6, d, e, f=5*6, g=f*h, h"
 PASS Valid:   "function f() { while (0) var a, b, c=6, d, e, f=5*6, g=f*h, h }"
 PASS Invalid: "var a = if (b) { c }"
 PASS Invalid: "function f() { var a = if (b) { c } }"
 PASS Invalid: "var a = var b"
 PASS Invalid: "function f() { var a = var b }"
-FAIL Valid:   "const a = b += c, a, a, a = (b - f())" should NOT throw
-FAIL Valid:   "function f() { const a = b += c, a, a, a = (b - f()) }" should NOT throw
+FAIL Valid:   "const a = b += c, a, a, a = (b - f())" should NOT throw 
+FAIL Valid:   "function f() { const a = b += c, a, a, a = (b - f()) }" should NOT throw 
 PASS Invalid: "var a %= b | 5"
 PASS Invalid: "function f() { var a %= b | 5 }"
 PASS Invalid: "var (a) = 5"
 PASS Invalid: "function f() { var (a) = 5 }"
 PASS Invalid: "var a = (4, b = 6"
 PASS Invalid: "function f() { var a = (4, b = 6 }"
 PASS Invalid: "const 'l' = 3"
 PASS Invalid: "function f() { const 'l' = 3 }"
 PASS Invalid: "var var = 3"
 PASS Invalid: "function f() { var var = 3 }"
@@ skipping 107 matching lines @@
 PASS Invalid: "for (var a = -6, b in b) break"
 PASS Invalid: "function f() { for (var a = -6, b in b) break }"
 PASS Invalid: "for (var a, b = 8 in b) break"
 PASS Invalid: "function f() { for (var a, b = 8 in b) break }"
 PASS Valid:   "for (var a = (b in c) in d) break"
 PASS Valid:   "function f() { for (var a = (b in c) in d) break }"
 PASS Invalid: "for (var a = (b in c in d) break"
 PASS Invalid: "function f() { for (var a = (b in c in d) break }"
 PASS Invalid: "for (var (a) in b) { }"
 PASS Invalid: "function f() { for (var (a) in b) { } }"
-PASS Valid:   "for (var a = 7, b = c < d >= d ; f()[6]++ ; --i()[1]++ ) {}"
-PASS Valid:   "function f() { for (var a = 7, b = c < d >= d ; f()[6]++ ; --i()[1]++ ) {} }"
+FAIL Valid:   "for (var a = 7, b = c < d >= d ; f()[6]++ ; --i()[1]++ ) {}" should NOT throw 
+FAIL Valid:   "function f() { for (var a = 7, b = c < d >= d ; f()[6]++ ; --i()[1]++ ) {} }" should NOT throw 
 try statement
 PASS Invalid: "try { break } catch(e) {}"
 PASS Invalid: "function f() { try { break } catch(e) {} }"
 PASS Valid:   "try {} finally { c++ }"
 PASS Valid:   "function f() { try {} finally { c++ } }"
 PASS Valid:   "try { with (x) { } } catch(e) {} finally { if (a) ; }"
 PASS Valid:   "function f() { try { with (x) { } } catch(e) {} finally { if (a) ; } }"
 PASS Invalid: "try {}"
 PASS Invalid: "function f() { try {} }"
 PASS Invalid: "catch(e) {}"
@@ skipping 115 matching lines @@
 PASS Invalid: "function f() { var a.b = c }"
 PASS Invalid: "var a.b;"
 PASS Invalid: "function f() { var a.b; }"
 FAIL e.line should be 1 (of type number). Was undefined (of type undefined).
 PASS foo is 'PASS'
 PASS bar is 'PASS'
 PASS successfullyParsed is true
 
 TEST COMPLETE